Question

part 1 of 1 8 points A car is moving at 17 m/s along a curve on a horizontal plane with radius of curvature 46 m. The acceleration of gravity is 9.8. What is the required minimum coefficient of static friction between the road and the car's tires to keep the car from skidding? Question 13 part 1 of 1 8 points A 36 g ball is fastened to one end of a string 79 cm long and the other end is held fixed at point O so that the string makes an angle of 22° with the vertical, as in the figure. This angle remains constant as the ball rotates in a horizontal circle. The angle & would remain constant only for a particular speed of the ball in its circular path. The acceleration of gravity is 9.8 m/s?. 9.8 m/s? 79 cm 36 8 Find this speed v. Answer in units of m/s.

Answer 1

The frictional force is, F = UN = umg The centripetal force is balanced by friction my2 R umg U= 12 Rg (17) 46(9.8) = 0.641

13)A) The radius of the circular path is, r=Lsin From Newton seconds law the net vertical force exerted on the ball is, EF, ET cos 8-mg 0=T cos - mg mg cos e T=- The net horizontal force exerted on the ball is, mv2 EF --T sine 1 my2 0= -T sin 11 T= my2 r sin e my2 mg r sine cose sin e cose v2 =rg =rg tan V=Vrgtan L sin egtan 79x102)(9.8)sin (22) tan (22) = 1.08m/s =